Synthesis of amine functionalized graphite nanosheets and their water-soluble derivative for drug loading and controlled release

Abstract

A facile route to synthesize amine (-NH 2 ) functionalized graphite nanosheets (AFGNS) by 2-step controlled chemical modification of microcrystalline graphite is described. The method begins with nitration by mixed acid (HNO 3 : H 2 SO 4 in 1 : 1 v/v ratio), followed by reduction with Na 2 S to form AFGNS. The AFGNS was reacted with carboxylic acid-terminated polyethylene glycol (PEG) chains (MeO-mPEG-COOH, M W = 5000 Da) in the presence of a carbodiimide coupling agent to obtain a water-soluble PEGylated AFGNS (P-AFGNS) composite.Anticancer drug doxorubicin (DOX) was loaded on this composite with a loading capacity of 0.296 mg mg À1for an initial concentration of 0.232 mg mL À1 DOX and 0.136 mg mL À1 of P-AFGNS and the release of DOX from this water-soluble DOX loaded P-AFGNS composite at two different temperatures was found to be strongly pH dependent.

MnO2 nanowires anchored on amine functionalized graphite nanosheets: highly active and reusable catalyst for organic oxidation reactions

“…The peak at 21.7 for an inter planar distance of 4.1 Å is due to intercalation of few -NH 2 group in between the nanosheets during synthesis of AFGNS. 13,37 It is noteworthy to mention here that in case of MnO 2 there is an increase in the ratio of the intensities of ( 110) and (101) diffraction peaks compared to the conventional value (3.4 versus 1.25 calculated with respect to counts). This indicates the oriented growth of the MnO 2 NP along the (110) plane leading to the formation of nanowires.…”

“…42 The D/G ratio was $0.25 which was attributed to the functionalization of GNS with -NH 2 group in AFGNS. 37 However, along with the peak due to D-band, a smaller hump was observed at 1220 cm À1 due to disordered graphitic lattice (A 1g symmetry or polyenes) in the Raman spectrum of MnO 2 @AFGNS. 42 The origin of this peak is believed to be due to some deformation in the nanosheets of AFGNS owing to self limiting redox reaction between KMnO 4 and AFGNS.…”

“…The synthesis was done following our previously reported method. 37 For synthesis of AFGNS, initially 200 mg of microcrystalline graphite powder was ultrasonicated with 200 mL of 1 : 1 (v/v) mixed H 2 SO 4 (36 N) and HNO 3 (16 N) in an ultrasonic bath for 30 min and then stirring at 25 C for 24 h for synthesis of -NO 2 functionalized GNS. The solution was then quenched in 1 L of distilled water and ltered through 0.22 mm PVDF membrane and washed until the ltrate reached neutral pH.…”

“…21 The high resolution O 1s spectrum (Fig. 2b) upon deconvolution by Voigt function 37 shows peaks at 529.7 eV corresponding to Mn-O-Mn and 532.3 eV for the oxygen containing functional groups such as -OH and -COOH. 47,48 As already mentioned earlier, the KMnO 4 being a very strong oxidizing agent, it creates some -OH and -COOH groups on the surface of AFGNS which is the reason for the origin of the peak at 532.3 eV.…”

Carboxylic acid terminated, solution exfoliated graphite by organic acylation and its application in drug delivery

“…DOX was loaded onto SEGn-FC-Na following a procedure described in our earlier report. 41 In this process, 0.15 mg mL −1 of SEGn-FC-Na in water was sonicated with DOX solution of initial concentration 0.22 mg mL −1 at neutral pH (pH = 7) for 30 min. This solution was then stirred for 24 h in dark at room temperature (25 • C).…”